WASHINGTON (Reuters) - People who eat a lot of red meat and
processed meats have a higher risk of several types of cancer,
including lung cancer and colorectal cancer, U.S. researchers
reported on Monday.

The work is the first big study to show a link between meat
and lung cancer. It also shows that people who eat a lot of
meat have a higher risk of liver and esophageal cancer and that
men raise their risk of pancreatic cancer by eating red meat.

"A decrease in the consumption of red and processed meat
could reduce the incidence of cancer at multiple sites," Dr.
Amanda Cross and colleagues at the U.S. National Cancer
Institute wrote in their report, published in the Public
Library of Science journal PLoS Medicine.

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The researchers studied 500,000 people aged 50 to 71 who
took part in a diet and health study done in conjunction with
the AARP, formerly the American Association for Retired
Persons.

After eight years, 53,396 cases of cancer were diagnosed.

"Statistically significant elevated risks (ranging from 20
percent to 60 percent) were evident for esophageal, colorectal,
liver, and lung cancer, comparing individuals in the highest
with those in the lowest quintile of red meat intake," the
researchers wrote.

The people in the top 20 percent of eating processed meat
had a 20 percent higher risk of colorectal cancer -- mostly
rectal cancer -- and a 16 percent higher risk for lung cancer.

"Furthermore, red meat intake was associated with an
elevated risk for cancers of the esophagus and liver," the
researchers wrote.

These differences held even when smoking was accounted for.

"Red meat intake was not associated with gastric or bladder
cancer, leukemia, lymphoma, or melanoma," added the
researchers, whose study is freely available on the Internet at
http://medicine.plosjournals.org/perlserv/?request=get-document&
doi=10.1371/journal.pmed.0040325.

Meats can cause cancer by several routes, the researchers
noted. "For example, they are both sources of saturated fat and
iron, which have independently been associated with
carcinogenesis," the researchers wrote.

Meat is also a source of several chemicals known to cause
DNA mutations, including N-nitroso compounds (NOCs),
heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons
(PAHs).

Jeanine Genkinger of Georgetown University in Washington,
D.C., and Anita Koushik of the University of Montreal said the
findings fit in with other research.

"Meat consumption in relation to cancer risk has been
reported in over a hundred epidemiological studies from many
countries with diverse diets," they wrote in a commentary.